Superdove!: The Straight Poop on Pigeons

Courtney Humphries talks about her new book, Superdove: How the Pigeon Took Manhattan...And the World. Plus, we'll test your knowledge of some recent science in the news. Web sites mentioned in this episode include www.birds.cornell.edu/pigeonwatch; chumphries.org

Courtney Humphries talks about her new book, Superdove: How the Pigeon Took Manhattan...And the World. Plus, we'll test your knowledge of some recent science in the news. Web sites mentioned in this episode include www.birds.cornell.edu/pigeonwatch; www.chumphries.org

Podcast Transcription

Steve: Welcome to Science Talk, the weekly podcast of Scientific American for the seven days starting August 13th 2008. I'm Steve Mirsky. It's been called the rat with wings—it's the pigeon, which is actually a kind of dove—has a rich history of[and] probably very fertile future. Journalist Courtney Humphreys became so fascinated with the ubiquitous bird that she wound up writing the new book Superdove: How the Pigeon Took Manhattan...And the World. We spoke in Manhattan in the Scientific American library.

Steve: Courtney, good to talk to you today.

Humphries: Thanks, Steve. It's good to be here.

Steve: So, let me just quote from your book. Pigeons were a fact I had taken for granted and the rest of the book really kind of springs from that and pigeons; we all take pigeons for granted, really but it's fascinating: how are they doing what they do? Why are they so successful in our modern urban environment?

Humphries: Yes, well, pigeons have actually a very long, complicated history with people and there are a few instances why they do so well in cities and why they're found very abundantly in cities all over the world. Some of that is just a, sort of, just a happy accident. Pigeons—their original environment is living on cliff sides and rocks and it just so happens that people have built buildings that are perfect home[s] for pigeons because they have nooks and crannies and things that imitate natural cliffs. Also, pigeons are granivorous so they eat grains and seeds and it happens to be that people have built their civilization on agriculture, so pigeons have plenty of food around when they're near people. But also, people have had a role in making pigeons as successful as they are today. And that's one of the things I was interested in with this book is that pigeons have been domesticated for thousands of years by people and in that process, people have really actually given them some qualities that make them such great—well, pests—like us today in the city.

Steve: Such great (unclear 2:16).

Humphries: Yes, exactly.

Steve: So, what are some of those qualities that make them so good at surviving among us?

Humphries: Well, you know, when they were domesticated animals, they were selected to be able to breed abundantly, so...

Steve: We should point out, because they were being eaten.

Humphries: Yeah. So you know, normally, you want your domesticated animal to produce itself, reproduce itself over and over, so, you know, when pigeons get into the cities, they can actually breed all year around in a lot of cases. They also would have been bred to survive in really confined areas like lofts. And so they are hardy animals; disease resistant, you know, they can, you know, reproduce and then also live in these very dense communities. What is interesting about pigeons is that even though they were domesticated, the way they were domesticated, they could also fly so freely during the day and they would often, you know, they might be kept in your farm and then they would go out and feed on the fields during the day for themselves. They never lost their ability to find food for themselves. So, we really bred this bird that could live in cities, was used to people, so could tolerate noise, could tolerate being around people, can breed like heck and they can also go and find food for themselves. So they really are perfect urban birds.

Steve: We created this Frankenstein that a lot of people complain about today.

Humphries: Yes, in a lot of ways we did and through this process of domestication and then gradually pigeons have become wild again. So, you know, the pigeons that are here in New York, they were brought here for food originally. They are not native here. They were brought over from Europe, but they were able to live on their own and have eventually become field pigeons. So, they live around people and they depend on people to some so extent, but they are not domesticated anymore, they are wild.

Steve: So, there's actually still a lot of interesting science, really there's a whole bunch of cultural stuff related to pigeons that you get into in the book. There is also a lot of science. For example, you know, their famous ability to home to, you know... one guy describes putting them on turntables to confuse them further while he drives a 100 miles away from home, and they still find their way home.

Humphries: Yes, they have an uncanny ability. You know, scientists have tried always different experiments. They put goggles on them, you know, they do all these things to try to mess up their ability to find their way home and they are very good at getting back home.

Steve: There's this Cornell researcher you discussed whose research project, sort of, developed out of his attempts to get rid of them, but they just kept coming back.

Humphries: Yes, I know, they're amazing and a lot of those are specially bred homing pigeons that they are using but it really is the same species as that you see on the street. They've just been, they've been bred for about a hundred years or so to be a little bigger, stronger, and they're trained, so they're very good at coming back, but all pigeons have the ability.

Steve: But we still don't really understand how they do it, do we?

Humphries: It's not fully understood. I mean, there are... they have this magnetic compass, a sort of built-in compass where they can actually use the Earth's magnetic field to orient themselves and they also use the sun to orient themselves, but they also find their way home using a variety of ways like roads, you know, they use landmarks, especially when they are closer to home, when they can see things that they've seen before. They also rely on smell, but that's not really clear, how each pigeon does this.

Steve: So, each individual one might be doing it in a totally individual way.

Humphries: Yeah, they might be relying on different qualities or different abilities that are... that they have, you know, whether the sun is out that day, maybe they're relying on the sun a bit more. But they have a lot of different ways of doing it, so if, you know, it's a cloudy day, they could still get home even if they can't see the sun.

Steve: You tell this amazing story in this book about attempts B.F. Skinner was involved, who basically had guided missiles—bombs—that pigeons would be the pilot of.

Humphries: Yeah. That's kind of an amazing story because it's true and it just sounds so fantastic, but B. F. Skinner did have a project in regard to develop[ing] a pigeon-guided missile and it seemed like it was working pretty well. I mean, he trained these pigeons to be able to find a target, you know, they would be somehow, in this missile, looking at a target on the screen and because they have been trained to peck on this target and to get food in response to that, they picked up this training so well that they would be very reliable pilots,

Steve: That project really didn't come to fruition but it did lead Skinner onto the path that he eventually became famous for.

Humphries: Yeah, yeah. He really liked working with pigeons. He just found them to be great. Before that, you know, a lot of behavioral psychologists had been working with rats, but he really liked pigeons, he thought they were great laboratory subjects, so there's... there were[was] a lot of laboratory research working with pigeons to see if they can shape their behavior in different ways, to see if they can understand certain things in what they see visual[ly], research in pigeons, and a lot of it came out of this work that Skinner did.

Steve: Darwin famously begins The Origin of Species with a long discussion of artificial selection in pigeon breeding. But you also talk about that in your book. You also talk about the fact that there's ongoing evolutionary research that involves pigeons.

Humphries: Yeah. I mean, there is, I mean, I think it actually is making a little bit of a comeback now, because for a long time, you know, Darwin was so fascinated with pigeons, because we're talking here about fancy pigeons, which a lot of people don't even know about. There are these breeds of pigeons that are so amazingly diverse, in shape, in color and you know their feathers, but you wouldn't even recognize some of these as pigeons. And Darwin was so fascinated because they all came from a single species and yet they looked so different, and so to him it was kind metaphor for the evolutionary process. You know, I was surprised to find that few scientists have studied fancy pigeons since him. I mean, there's been a few papers here and there on the color of all these pigeons, and on the genetics of their coloration, but I think I have talked to a couple of scientists who are now picking this up as a new model that can be used to understand evolution, to understand the genetics of it, the developmental biology of all these different shapes, you know, that pigeons can take on. So they're, you know, like dogs. They're actually very friend able species that can take on all these different shapes and sizes, so they're a perfect model for studying how the evolutionary process takes place.

Steve: You studied pigeons all over the world; you went to Italy, New York, and Boston, and Asia. You have looked for pigeons while there.

Humphries: Yeah. Well, I had mentioned Asia because that was a trip I had taken, this was actually before I was interested in pigeons at all, but it was my initial travel that I had done a few years ago where I started to see pigeons everywhere in the world—and at least everywhere I went in these big cities—and so, that kind of got me thinking about it. But I did work in particular pigeons which live in Europe and here in North America.

Steve: Those are all the same species.

Humphries: It's all the same species. I mean, yeah, there are other types of pigeons and doves that are very common, you know, mourning doves, and over Europe, they have the collared dove, which is also invading a lot of areas, but the stereotypical pigeon in the city that you see is very recognizable, is all the same species.

Steve: What got into your skin to the point so you were motivated to actually write a book about them?

Humphries: Well, I think it was actually discovering a lot of really interesting information about them, because I kind of have had the attitude that they were just a very mundane animal, like a lot of people. I had seen them in my travels, as I said. I had seen them all throughout Europe and they just seem to be always there and kind of... I think most people think of them as a kind of humorous, kind of, odd thing.

Steve: Well you talk about them, the stereotypical New Yorker cartoon...

Humphries: Yeah.

Steve: ...that features a cheeky urban pigeon that's kind of a wisecrack.

Humphries: Yes, yeah, exactly, and it's kind of the same way. In fact, I remember being in Europe and seeing pigeons in St. Mark's Square in Venice and thinking, actually, being kind of interested in how they're behaving and, you know, I felt a little embarrassed and interested in them. They are just not the kind of, you know, the kind of thing that people are normally interested in.

Steve: Right.

Humphries: So, I think that what got me interested in the book is just every time I looked up something about pigeons, I came up with something like that B. F. Skinner story or about a pigeon-guided missile, or came up with these fancy pigeons that just looked you know, crazy, and then I found out that Darwin himself had bred some of these pigeons and so, it just turned into a really interesting story that I realized that they actually have a very, very interesting evolutionary history with people, and that the actual things that make them seem boring to us because they are everywhere, in a way it makes them even more interesting because they are so successful.

Steve: You tell the story of going to see some falcons being abandoned and finally feeling comfortable putting your binoculars up just to see the bird because you would, if you notice that people thought it is strange that you would look at pigeons at all.

Humphries: Yeah!

Steve: And that bird watchers pay any attention at all, so there is an ongoing project, you talk about some research towards the end of the book that's actually a pigeon-related project that even little kids can take part in.

Humphries: Yeah, Yes, it's called Project Pigeon Watch and that's run by Cornell Ornithology Lab and they do a few urban bird studies and it's really interesting because the questions they're looking at are real questions. Pigeons, street pigeons, are extremely diverse in their colors and I think if you even look out in New York and you'll see white ones, you'll see spotted ones, you'll see red ones, and there's a question about it; it seems that they actually use these colors to base their mate choice on. So, they seem have certain preferences when they choose their mates. So, that's a question science hasn't answered quite as yet, what those preferences are and why they have them. And Project Pigeon Watch enlists normal citizens and school children and you can go out and gather information about the color varieties that you see in your area and you can send them data and it can help them study these questions, which is a great way, I think, to get people interested in urban nature that's right around them.

Steve: So, of all the fascinating things, I mean, like, you know, the pigeon-guided missile really stood out a little bit...

Humphries: Yeah.

Steve: But of all the things you've learned over the course of researching the book, is there one thing that really just blew you away?

Humphries: Well, yeah, it's hard to top that missile but, I would say, you know, there are a lot of things that really surprised me. One of the thing he explains is that it had... that was actually surprising to me was actually going to see the wild rock pigeons living in Sardinia, which was something that I had never seen, you know, truly wild pigeons in the kind that we have in the cities that are feral, so they have been domesticated some time in their history and how now they live, they still live in the wild in a way and they have this slight history with people, and it was really interesting for me to see these wild pigeons because they really behave so differently. I mean, you can tell that they are pigeons because they have the same color, you know, iridescent feathers on the top, old black bar on their wings. They look like pigeons but they behave totally differently. They fly and they flitter around these cliffs. They live in the cliff sides. They are very shy and it was almost like watching bats the way they were flying and for me it was really interesting experiencing how the diverse their different behaviors could be depending on where they lived.

Steve: Yeah, the timidity must have been really shocking after the urban...

Humphries: Yeah.

Steve: ...pigeons we're used to that you have to sort of, step around.

Humphries: Yeah, and they are strolling out in the streets and they don't care at all.

Steve: I want to thank you for changing my view on pigeons a little bit anyway, because growing up in New York City I would watch pigeons run across the street when a cab would come and I would always think that the pigeon was emblematic to me of unfulfilled potential, because it could fly but it decided to run instead. So, now I see that that's part of their whole urban repertoire of survival skills.

Humphries: Just like us they have became a little sedentary in the city.

Steve: Now it's time to play TOTAL.....LY BOGUS... Here are four science stories but only three are true. See if you know which story is TOTALL....LY BOGUS.

Story number 1: A new species of bacteria has been discovered that lives only in human ears.

Story number 2: Researchers have created the world's thinnest balloon.

Story number 3: Researchers are trying to develop a tire for military vehicles that won't go flat if they're hit by an explosive, because the tires don't get filled with air.

And story number 4: The first virus has been discovered that infects another virus.

Time's up.

Story number 4 is true. There is a huge virus called a mimivirus that's actually as big as some bacteria and researchers have found another smaller virus living on it. They published their findings in the journal Nature. The smaller virus, dubbed Sputnik, causes the infected larger virus to produce deformed structures. For more, to see [the] August 6th article called "Even Viruses Get Sick" at www.SciAm.com.

Story number 3 is true. Future military vehicles may ride on airless tires. The nonpneumatic tires would be made of hard polymers in a honeycomb design so most of the tire space would actually, in fact, be air but just the regular old outdoor air. And since most of the tire's volume would be empty space, most shrapnel to hit the tire would go right through. And if up to 30 percent of the structure gets blown away the tire still functions. For photos and more info, check out the August 11th article at www.SciAm.com called "Airless Tire Promises Grace Under Pressure for Soldiers."

And story number 2 is true. The world's thinnest balloon is made of a layer of graphite—pencil lead—just one atom thick. What's really cool is that even the smallest gas molecule can't escape from the tight lattice of the graphite; so no leakage. Cornell physicist Paul McEuen led the team, that came up with the ultrathin chamber. He noted that it could be useful for hypersensitive pressure, light and chemical sensors or for filters making ultra pure solutions. Speaking of tires I like to bicycle, so I e-mailed McEuen and asked, could the membrane potentially be used as a coating for the interior of tires to stop the slow escape of pressurized gases within? And he e-mailed back: interesting idea, perhaps so. And again, sometimes pumping up the tires is a better workout than the bike ride.

All of which means that story number 1 about a new species of bacteria that lives only in human ears is TOTALLY....BOGUS, because what is true is that a new bacterial species has been found in the human mouth. The finding was published in the August issue of the International Journal of Systematic and Evolutionary Microbiology, which itself is a mouthful. Understand the new bacterium could lead to new insights into tooth decay and gum disease, to which we can all say, aah....

Well, that's it for this edition of the weekly SciAm podcast. Visit www.SciAm.com for the latest science news, opinion and content from all our magazines. For Science Talk, the weekly podcast of Scientific American, I'm Steve Mirsky. Thanks for clicking on us.